I am interested in the following peptide N-carbobenzoyl-Ile-Glu-(OtBu)-Ala-Leu-CHO. It isnt too difficult to synthesize, however, the purification is the difficult part. 90% can be done but when trying to go above that (the target is 95%), the purity drops. It is very prone to racemization as well.
We used 0.1% TFA in 100% acetonitrile and 0.1% TFA in 100% water to purify the peptide, and methanol. Is there a better process or some sort of special technology we're missing here? Does anyone have the complete purification procedure from start to finish?